The present invention relates to article conveying systems wherein an article is transferred from a first position to a second position. More particularly, this invention is directed toward a transfer screw used for transferring articles from a clean room to a less clean room wherein the screw is capable of conforming to different size articles for transferring the same. Accordingly, if it is desired to transfer a new and different size article between the rooms, the screw does not have to be changed to accomplish this end.
The conveyance of articles from a clean room to a less clean room such as during the bottling of pharmaceuticals poses problems for typical conveying systems. Typical conveying systems usually incorporate the use of a continuous and moving belt. Because a belt conveyer moves in a repetitive circular manner, if it were to be used between a sterile and a less sterile environment, the belt would tend to transfer contaminants from the less sterile room back to the more sterile room. Accordingly, the cleaner environment would become contaminated. Therefore, it is necessary to transfer articles from a clean room to a less clean room in a different manner.
A screw extended longitudinally between the clean and less clean rooms can accomplish this result. However, most screws are of the substantially rigid variety wherein only a screw having a pitch which accommodates the size of the article to be transferred can be used. As such, if it is desired to transfer a different size article, which can be accomplished when using belt-transfer methods, it is necessary to change the screw to accommodate the different size.
The prior art does include screws used to transfer materials from a first position to a second position. However, in the prior art, the screws are generally used to transfer granular materials in an auger-type machine. These screws do have some degree of longitudinal flexibility but are limited by being attached to a central core or being formed from a substantially inflexible material. Nevertheless, the screws in the prior art which are flexible are not used for the same purpose as the screw disclosed in this invention.
For example, U.S. Pat. No. 3,802,551 to Summers discloses a screw for transporting granular material from one point to another point. To avoid breakage of the screw, the Summers invention allows the screw to deform upon start-up to adjust to the initial load of the granular material being transported. However, the Summers screw is of limited flexibility and is not designed to conform to different size articles.
U.S. Pat. No. 4,611,532 to Trinkley discloses a device that resembles a screw. However, it is not used for longitudinal transfer. Trinkley discloses a food separating device comprised of a central core having circular blades attached thereto for moving and aligning articles of food passing under the device. The blades are comprised of a flexible material which conforms in some degree to different size food articles. However, the device in Trinkley is not used for, nor is it capable of, transferring articles in a longitudinal direction along the length of the screw. In both Summers and Trinkley, the flights of the screw are rigidly attached to a central core which limits the flexibility of the flights in the axial direction.
U.S. Pat. No. 5,099,986 to Kuzab and U.S. Pat. No. 4,819,578 to Koisaw, et al. also disclose semi-flexible screws for transporting granular materials. Again, these screws lack the ability to substantially conform to larger articles and are used only for granular substances.